Electric tank heater



FIG. 1 is a perspective view of an electric tank heater illustrating the present design;

FIG. 2 is a top plan view of the electric tank heater shown in FIG. 1;

FIG. 3 is a bottom plan view of the electric tank heater shown in FIG. 1;

FIG. 4 is a front elevational view of the electric tank heater shown in FIG. 1;

FIG. 5 is a rear elevational view of the electric tank heater shown in FIG. 1;

FIG. 6 is a left side elevational view of the electric tank heater shown in FIG. 1; and,

FIG. 7 is a right side elevational view of the electric tank heater shown in FIG. 1. 

The ornamental design for an electric tank heater, as shown and described. 